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kernel: add emphasis to nano_sem_take/k_sem_take return code difference

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The reversal of the meaning of a value of 0 from k_sem_take vs
nano_sem_take has caused some issue when porting code from the legacy
API to the new API, so put some emphasis on this difference.

- Add a note in the API description.
- Put the call to k_sem_take and the reversal of the return value inside
  of nano_sem_take on one line so that grepping on it shows the
  reversal.

Change-Id: I2f4ba58dc087176d68b55371fa6e367b72559e70
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>
This commit is contained in:
Benjamin Walsh 2016-12-01 11:39:49 -05:00 • committed by Anas Nashif
commit 91f834c908
2 changed files with 9 additions and 2 deletions
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6
include/kernel.h
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@ -1694,6 +1694,12 @@ extern void k_sem_init(struct k_sem *sem, unsigned int initial_count,
* @param timeout Waiting period to take the semaphore (in milliseconds),
* or one of the special values K_NO_WAIT and K_FOREVER.
*
* @note When porting code from the nanokernel legacy API to the new API, be
* careful with the return value of this function. The return value is the
* reverse of the one of nano_sem_take family of APIs: 0 means success, and
* non-zero means failure, while the nano_sem_take family returns 1 for success
* and 0 for failure.
*
* @retval 0 Semaphore taken.
* @retval -EBUSY Returned without waiting.
* @retval -EAGAIN Waiting period timed out.